1. Field of the Invention
The present invention relates generally to a method of dispersing Cesium-131 (Cs-131), including preparing particles of radioactive powder containing Cs-131. Uses of the dispersed Cs-131 prepared by the method include cancer research and treatment, such as for use in brachytherapy implant seeds and other sources independent of method of fabrication.
2. Description of the Related Art
Radiation therapy (radiotherapy) refers to the treatment of diseases, including primarily the treatment of tumors such as cancer, with radiation. Radiotherapy is used to destroy malignant or unwanted tissue without causing excessive damage to the nearby healthy tissues.
Ionizing radiation can be used to selectively destroy cancerous cells contained within healthy tissue. Malignant cells are normally more sensitive to radiation than healthy cells. Therefore, by applying radiation of the correct amount over the ideal time period, it is possible to destroy all of the undesired cancer cells while saving or minimizing damage to the healthy tissue. For many decades, localized cancer has often been cured by the application of a carefully determined quantity of ionizing radiation during an appropriate period of time. Various methods have been developed for irradiating cancerous tissue while minimizing damage to the nearby healthy tissue. Such methods include the use of high-energy radiation beams from linear accelerators and other devices designed for use in external beam radiotherapy.
Another method of radiotherapy includes brachytherapy. Here, substances in the form of seeds, needles, wires or catheters are implanted permanently or temporarily directed into/near the cancerous tumor. Historically, radioactive materials used have included radon, radium and iridium-192. More recently, the radioactive isotopes Cs-131, iodine (I-125), and palladium (Pd-103) have been used. Examples are described in U.S. Pat. Nos. 3,351,049; 4,323,055; and 4,784,116.
During the last 30 years, numerous articles have been published on the use of I-125 and Pd-103 in treating slow growth prostate cancer. Despite the demonstrated success in certain regards of I-125 and Pd-103, there are certain disadvantages and limitations in their use. While the total dose can be controlled by the quantity and spacing of the seeds, the dose rate is set by the half-life of the radioisotope (60 days for I-125 and 17 days for Pd-103). For use in faster growing tumors, the radiation should be delivered to the cancerous cells at a faster, more uniform rate, while simultaneously preserving all of the advantages of using a soft x-ray emitting radioisotope. Such cancers are those found in the brain, lung, pancreas, prostate and other tissues.
Cesium-131 (Cs-131) is a radionuclide product that is ideally suited for use in brachytherapy (cancer treatment using interstitial implants, i.e., “radioactive seeds”). The short half-life of Cs-131 makes the seeds effective against faster growing tumors such as those found in the brain, lung, and other sites (e.g., for prostate cancer).
Cesium-131 is produced by radioactive decay from neutron irradiated naturally occurring Ba-130 (natural Ba comprises about 0.1% Ba-130) or from enriched barium containing additional Ba-130, which captures a neutron, becoming Ba-131. Ba-131 then decays with an 11.5-day half-life to cesium-131, which subsequently decays with a 9.7-day half-life to stable xenon-130.
Due to the need for dispersed Cs-131 and the deficiencies in the current approaches in the art, there is a need for improved methods. The present invention fulfills this need and further provides other related advantages.